A smart key may allow a driver to open and close a vehicle door or start a vehicle engine without having to insert a key into a key box, or ignition, or perform additional manipulation for operation. Examples of the smart key may include a smart card that is easy to carry or a smart key for a wireless communication, such as a fob.
When a driver carrying a smart key approaches a vehicle, the smart key may perform a radio frequency communication and another radio frequency communication between the vehicle and the smart key such that a locking mechanism is automatically released. As a result, the driver may open the door without inserting an additional key, and may start the engine without inserting a starting key after entering into the vehicle.